1. Field of the Invention
The present invention relates to a method and apparatus for cleaning semiconductor devices and, more particularly, to a method and apparatus for cleaning semiconductor devices using an ultrasonic pure water (to be referred to as megasonic pure water) added with an alkaline or acidic chemical.
2. Description of the Related Art
Interelement wiring gaps in semiconductor devices have been reduced along with an increase in their integration, and a term "0.5-.mu.m rule" is often in recent years. For this reason, foreign substances, i.e., dust formed during the manufacture cannot be neglected and may give a substantial influence on a product yield. Various improvements have been made in cleaning in the manufacturing process to minimize the amount of dust produced in the manufacturing stages.
In addition to a conventional cleaning method using a pure water flow, a megasonic pure water cleaning method is also utilized. When a megasonic pure water cleaning apparatus is used, a frequency range of very short vibration wavelengths of 800 kHz to 2 MHz is used and even fine particles can be efficiently removed. In addition, no cavitation occurs, and the damage to the semiconductor substrate can be prevented.
However, when RIE (Reactive Ion Etching) or CDE (Chemical Dry Etching) is performed to etch an Al or Al alloy wiring layer or an SiO.sub.2 or P-SiN (Plasma-SiN) insulating film by using a resist, and the resist is then removed by the oxygen plasma method, a resist residue and a heavy metal residue left in the above process cannot be removed by megasonic pure water cleaning. Therefore, a post treatment such as a treatment with an alkaline solution such as a choline solution or an acidic solution such as a hydrofluoric acid or sulfuric acid solution is required after megasonic pure water cleaning is performed.
Since the post treatment is performed by a dip method, particles floating on the surface of the solution by a surface tension may be attached to the cleaned semiconductor substrate again.